Variable size,multi-hinge centralizer

ABSTRACT

A device for centering well pipes in a well bore or casing with spring bows extending between spaced collars which are adapted for mounting on the well pipe wherein each collar is assembled from a multiplicity of releaseable hinge-connected segments to create a circumference which will closely encircle the well pipe with the number of segments being variable for accommodating different sizes of well pipe and the arcuate shape of each segment not necessarily conforming to the well pipe. Each spring bow extends between and is mounted on one segment of each collar.

United States Patent 1 [72] Inventor James R. Solum Huntington Beach, Calif. [21] Appl. No. 752,117 [22] Filed July 22, 1968 [45 Patented Mar. 2, 1971 [73] Assignee B & W Incorporated Torrance, Calif. Continuation of application Ser. No. 576,055, Aug. 30, 1966, now abandoned.

[54] VARIABLE SIZE, MULTI-HINGE CENTRALIZER 15 Claims, 11 Drawing Figs. [52] US. Cl 166/241, 166/315 [51] Int. Cl E21b 17/10 [50] Field of Search 166/170, 172-6, 241, 315; 308/4 (A) [56] References Cited UNITED STATES PATENTS 1,820,391 8/1931 Hartman 308/4 1,894,519 1/1933 McLaine 308/7 2,145,336 l/l939 Boyd 308/4 2,594,550 4/1952 Gist 166/241 2,727,576 12/1955 Hall 166/241 2,738,019 3/1956 Atkinson. 166/241 3,072,195 1/1963 Kluck 166/241 3,108,639 10/1963 Brooks 166/241 Primary Examiner-Marvin A. Champion Assistant Examiner-Jan A. Calvert Attorney-Lyon & Lyon ABSTRACT: A device for centering well pipes in a well bore or casing with spring bows extending between spaced collars which are adapted for mounting on the well pipe wherein each collar is assembled from a multiplicity of releaseable hingeconnected segments to create a circumference which will closely encircle the well pipe with the number of segments being variable for accommodating different sizes of well pipe and the arcuate shape of each segment not necessarily conforming to the well pipe. Each spring bow extends between and is mounted on one segment of each collar.

VARIABLE SIZE, MULTLHINGE CENTRALIZER CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of my copending application Ser. No. 576,055, filed Aug. 30, 1966, entitled Variable Size, Multi-Hinge Centralizer" now abandoned.

This invention relatesto centralizers for use on well pipe in centering the pipe in a well bore and, in particular, is directed to a centralizer device comprised of a multiplicity of hinged segments joined to form pipe fitting collars of any desired size by the addition or subtraction of segments.

Devices known as centralizers have long been in use in the oil industry for centering well pipe in or spacing well pipe from the wall of the well bore particularly when cementing the well pipe in the well bore. The most common conventional centralizers are comprised of two spaced. collars adapted to fit the exterior of the well pipe withoutwardly bowed staves extending between the collars to engage the well" bore thereby resiliently centering the well pipe. Since thereare.approximately25 different standard sizes of well pipe used in the oil industry, it has been necessary to provide a different centralizer for each well pipe size thereby presenting substantial problems in maintaining adequate inventories of all sizes at various locations for im'r mediate availability. Moreover the size, shape and number of spring bows used on a centralizer for a given well pipe size may ideally differ depending on the well bore size, the degrees of slant. in the well bore, and other conditions to be encountered. For example if the well bore is substantially larger than. the well pipe, the spring bows must bow outwardly further to establish centering engagement than if the well bore were smaller. As a result it is not uncommon for a manufacturer to offer three of four different shapes of spring bows in his line of centralizers to accommodate the particular requirements thereby further compounding the problem ofmaintaining an adequate stock of all 25 sizes of each of the three or four styles of centralizers.

Another practical problem with conventional centralizers is the cost of shipping due to their bulky cagelike shape. Moreover if the wrong size conventionalcentralizer is shipped or the programmed well pipe size is changed in the interim, there is no convenient or practicalway inwhich the size of a given conventional centralizer can be modified to fit a different size well pipe.

Accordingly it is a principal object of this invention to pro vide a novel form of centralizer wherein the collars are comprised of a multiplicity of releasably connectedsegments with each spring bow mounted on a segment of each collar whereby the size of the collars may be varied by adding or subtracting segments and any number or type of bows may be assembled withthe segments to form the desired centralizer.

Another object of this invention is to provide a novel form.

of centralizer construction wherein the collars are comprised of a multiplicity of arcuate segments hinged together and the desired collar size is obtained by selecting an appropriate number of arcuate segments from one or more of just a few sizes of segments. Still another object of this invention is to provide such a centralizer with spring bows adapted to be readily mounted on such arcuate segments whereby the desired bow profile and number of bows may be mounted ona given centralizer. A still further object of this invention is to provide such a centralizer wherein the spring bows are releasably mounted on such arcuate segments.

A further object of this invention .is to provide a novel form of centralizer construction wherein any number of tiers of bows may be mounted along the well pipe with a common collar between each tier of bows by means of the collars being comprised of a multitude of segments hinged together withthe bows attached toindividual segments, and on the common collar the bows of alternate segments extend in opposite directions from the collar.

It is a further objectof this invention to provide. a multiplici ty of each of a few different components from whicha wide variety of sizes and styles of centralizers can be readily and simply constructed without the need for special tools or equipment.

Other and more detailed objects and advantages of this invention will appear from the following description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of an assembled. centralizer of LhIS invention.

FIG. 2 is a perspective view of a modified embodiment of the centralizer of this invention comprised of similar components as the centralizer of FIG. 1 but assembled in a doubletier arrangement.

FIG. 3 is a perspective view of one of the basic components used in assembling centralizers of this invention comprising the spring bow and collar segments.

FIG. 4 is a composite view of three sizes of arcuate collar segments usable in constructing the various sizes of central- 12ers.

FIG. 5 is a fragmentary perspective view of two arcuate collar segments adaptedtobe hinged together for the centralizer.

FIG. 6 is a fragmentary elevation view of the hinge section of the segments joined by a hinge pin.

FIG. 7 is a fragmentary end view of the hinge section.

FIG. 8 is an exploded perspective view of a modified form of collar segment and spring bow adapted. to be releasably assembled together for constructing a centralizer of this invention.

FIG. 9 is a sectional elevation view of the modified embodiment of. FIG. 8' in the assembled condition of the bow and segment.

FIG. 10 is a further modified embodiment of the arcuate segment and spring bow adapted to be releasably assembled together similar to the embodiment of FIG. Sand 9.

FIG. 11 is an elevation view of a rnulti-tiered centralizer constructed in accordance with this invention and mounted on a well pipe- Referring more particularly to FIG. 1, a typical centralizer, generally designated 10 is illustrated as constructed in accordance withthis invention. The centralizer 10 is comprised of a pair of collars 11. and. l2.connected by a plurality of longitudinally extending spring-bows 13. The collars 11 and 12 are axially spaced and aligned for slidably fitting the exterion of the particular well pipe that is to be centered in the well* bore. Normally a stopelement will be provided on the well pipe to locate the centralizer therealong. The spring bows or staves 13 are of a selected profile to produce the desired overall diameter at their midpoints and the necessary strength to accomplish the well pipe centering in the particular well bore under the expected conditions. If the size of the well bore were a great deal larger than the size of the well pipe than it is likely and conventional that a bow profile which bows outwardly substantially more than that which is depicted for bows 13 would be selected. As thus far described the structure and functions of centralizer l0 areconventional and well known to those skilled in the art.

By this invention means are provided for forming the collars 11 and 12 of the centralizer 10 of any desired diameter to fit the particular'wellpipe and, as shown in the drawings, these means include a multiplicity of individual arcuate segments .14 releasably joined into the collar shape. Each of the segments l4are curved in the circumferential direction to more closely fit the well pipe but it is to be noted that the radius of curvature of the segments need not be identical to the radius of the well pipe for the assembled collar to adequately fit the well pipe. If the radius of curvature of segments 14 is greater than the radius of the well pipe, itis obvious that theoretically only the center portion of each segment 14 will contact the well pipe whereas if the radius of curvature is less thanthe well.

pipe radius than the two edges of the segment will contact the well pipe. However in either casethe segments 14 are of such a short circumferential width that no portion of asegment is spaced any great distance from the well pipe surface. In this regard for example it has been found adequate to employ a 3 /einch radius of curvaturefor the arcuate segments 14 and.

although this would only perfectly fit a 7-inch diameter well pipe the fit of the segments is completely adequate for all well pipe sizes which normally range from 2%-inch diameter to 20- inch diameter In part this is practical since the segments 14 are relatively short in the circumferential direction.

The arcuate segments 14 are releasably joined together by any convenient means such as hinge sections 15 along each longitudinal edge of the segment. Referring for detailed clarity to FIGS. 5, 6 and 7 which show the same hinge sections illustrated in FIG. 1, each hinge section 15 is comprised of a half section 16 on one segment 14 and another half section 17 on the next adjacent arcuate segment 14. This results in each segments 14 having a half section 16 along one edge and a half section 17 along the other edge for mating with the hinge sections of adjacent segments on either side. Each hinge section 16 and 17 is comprised of three tubular elements 18 aligned and spaced along the longitudinal edge 19 of the arcuate segment. The tubular elements 18 may be of any convenient form and construction such as being integrally formed from the material of segments 14 by appropriately bending and forming tabs 20 back upon the segment and welding at 21.

Although it is not essential to this invention it is preferred that three tubular elements 18 be provided with each half hinge section 16 and 17 thereby forming a hinge 15 of six aligned tubular elements joined by a hinge pin 22. This provides the optimum balance between the stresses onthe tubular elements 18 and the hinge pin 22. The tubular elements 18 of half hinge section 16 obviously are offset from the tubular elements 18 of half hinge section 17 whereby they intermesh to receive the hinge pin 22. The lowermost tubular element 18 on half hinge section 16 is adjacent the lower edge of the segment 14 while the uppermost tubular element 18 of the hinge half section 17 is adjacent the upper edge of the segment 14 whereby the hinge half sections are actually reversible. That is, the segment 14 in the right hand portion of FIG. could be rotated 180 in the plane of the drawing and the half hinge sec tion identified as 16 thereon would properly mesh with the half hinge section 16 of the left hand segment 14 for connection by a hinge pin 22. This further enhances the versatility of this centralizer construction butis not absolutely essential. It will readily appear to those skilled in the art that although a particular hinge configuration is shown described any number of configurations of releasable connections could be readily employed without departing from this invention.

The arcuate segments 14 are held together in the assembled condition by hinge pins 22 which may have a head 23 and be bent over on the other end 24 to prevent inadvertent disassembly. Of course the last hinge pin 22 of each collar may be installed after the centralizer has been wrapped around the well pipe thereby avoiding the necessity of slipping the centralizer over the end of the well pipe. As an alternative to providing hinge pins 22 with a head 23 and of a length to bend over the end 24, the uppermost and lowermost tubular elements 18 of the hinge section may be provided with tabs 25 that are capable of being crimped inwardly to cover the end of the tubular element after a straight, unheaded'hinge pin has been inserted. When crimped the tabs 25 capture the hinge pin in the tubular elements.

In order to assemble a centralizer having collars l1 and 12 of a size for fitting the particular well pipe it is necessary to employ a multiplicity of arcuate segments 14 and by selecting the appropriate number of arcuate segments from two or three different widths of segments the desired collar size can be achieved. The typical well pipe sizes for which collars must be constructed as measured by their outside diameters are 2% inches, 2 /8 inches, 3%inches, 4 inches, 4%inches, 4% inches, 5 inches, 5%5% inches, 6 inches, 6% inches, 7 inches, 7% inches, 8% inches, 9 inches, 9% inches, 10% inches, 1 1% inches, 12% inches, 13% inches, 1.4 inches, l6 inches, 18 inches, 18% inches and 20 inches, although certain of these sizes are relatively uncommon. It has been found that collars to fit most of these well pipe sizes can be constructed from merely two widths of segments 14 but that a third width of segment 14 is advisable for constructing some sizes. Thus from the three different width segments 14a, 14b and shown in FIG. 4, collars may be constructed for each well pipe size by selecting the appropriate number of each segment width. Without limiting this invention a typical width for the intermediate size segment 1411 may be 3 inches between the center lines of the tubularelements 18 which leaves adequate space between the tabs 20 to receive a normal width spring bow 13. A smaller segmentl4a would be used merely as a size adjusting link whereas most of the sizes would be accomplished by an appropriate number of segments 14b or 14c or a combination of both. thus for example four arcuate segments 14b linked together will adequately fit a 2 /8 well pipe while four segments 14c linked together may properly fit a 3%well pipe and so forth.

A modular element or unit of the composite'centralizer 10 is comprised of a stave or spring bow l3 welded on each end at 26 to arcuate segments 14 as shown in FIG. 3. This form would be factory assembled and painted for shipping in stacked relationship which obviously would be more compact than the assembled relationship shown in FIG. 1. Field as sembly merely requires selecting the appropriate number of modular units which have the desired bow profile and widths of arcuate segments 14 and assembling with hinge pins 22. The entire centralizer 10 may be comprised of modular units whereby a bow 13 is attached to each of the arcuate segments 14 forming the collars as shown in FIG. 1 or blank segments 14 (without attached bows) may be interspersed between the modular units to provide a centralizer with fewer spring bows 13 where desirable This permits a careful selection and tailoring of the type and strength of centralizer installed at each location along a well pipe at the time of field installation which heretofore was impossible.

Referring more particularly to FIG. 2 a modified form of centralizer, generally designated 30, is constructed from the same components heretofore described for constructing the more conventional style centralizer of FIG. 1. Centralizer 30 is double tiered and in that respect is similar to a few heretofore conventional though uncommon centralizers. Centralizer 30 includes an upper collar 31, middle collar 32 and a lower collar 33 in axially spaced and aligned relationship. In the centralizer 30 shown each of the collars 31, 32 and 33 are comprised of eight individual arcuate segments 14 hinged together in the aforedescribed manner. The upper collar 31 and lower collar 33 are comprised of alternate segments 14 which are blank between segments which have spring bows 13 connected thereto. The middle collar 32 has bows 13 connected to each arcuate segment 14 with alternate bows extending in opposite directions. Since the hinge sections 16 and 17 of each hinge 15 are reversible as heretofore described it will readily appear to those skilled in the art that the modular units comprising the upper half of double-tiered centralizer 30 are the same as those comprising the lower half thereby further illustrating the versatility of this construction arrangement. Referring further to FIG. 11 a centralizer construction is shown which heretofore would have been impossible due to its ex treme bulk but is made possible by this invention since it may be assembled on the well pipe at the well site. The centralizer 40 of F I0. 11 is substantially similar to centralizer 30 of FIG. 2 but with two additional tiers assembled between the upper and lower tiers with three common or middle collars 41, 42 and 43 arranged similar to middle collar 32 with bows 13 extending in both directions therefrom. A factory assembled conventional centralizer similar to centralizer 40 would be 10 to l5 feet long thereby being completely impractical. I I

Referring now more particularly to FIG. 8 and 9, there is illustrated a modified arrangement for releasably connecting the spring bow 50 to the arcuate segment 51 although the bow 50 and segments 51 are similar in all other respects to the heretofore described bows 13 and segments 14. The arcuate segment 51 includes a large cutout portion 52, a small cutout portion 53 and a bridge element 54 between such cutout portions. The end of bow 50 is provided with a flat portion 55 and an outwardly. turned end 56. are of a circumferential. width adequate to receive the end of bow 50. The bow 50 is assembled to: the segment '51 by merely inserting the end of the bow through cutout portion 52,-.behind bridge element 54 and then pivoting the end 56 of the bow out through the cutout portion 53 as shown in FIG. 9. Once the plurality of bows 50 and segments 51 have been assembled to comprise a centralizer similar to centralizer with all of the connecting hinge pins in place, the bows 50 will not become detached from the segments 51 since the required pivoting for disassembly cannot be accomplished in this assembled condition and end 56 en'gagesthe upper abutment edge of bridge element 54 to, prevent withdrawal. By'this arrangement the number of different components necessary to construct all sizes and types of centralizers is reduced even further since the various styles of bows 50 need not be assembled to the particular width of arcuate segment 51 until it isdecided exactly a "the size and type centralizer desiredfor the particular situation.

. A further modified form of releasable connection between the spring bow anda'rcuatc segment similar to that shown in FIG. 8 and 9 is shown in FIG. 10. In this embodiment the spring bow 60 is provided with straight end'portion 65 but has hole 66 rather than the outwardly turned end 56 of the aforedescribed embodiment. The hole 66may be of any n desired shape. The arcuate segment 61 is again provided with a large cutout portion 62 and an outwardly deformed bridge portion 64. The bridge portion 64 is provided with an inwardly deformed tab"67 of a. shape for fitting the hole 66 in the how.

60. The how 60 isassembled to the arcuate segment 61 in a l similar fashion by inserting the bow through cutout portion 62 and pivoting in a clockwise direction as viewed in FIG. 10

"until the hole 66 is engaged by the abutment tab 67. Again the ponents. Although my invention has been described 'in connection with a few de tailed ernbodiments it is to be understood that my invention is not limited to the herein disclosed details but rather is of the full scope ofthe appendedclaims.

I claim:

' l. The combination of a centralizer and a well pipe compris:

ing a pair of axially spacedand aligned 'collar means mounted on the well pipe; each collar means comprising of a multiplicity of more than two separate segments releasably connected together and encircling the well pipe,'each segment being circumferentially curved'to a predetermined radius of curvature and having a center of curvature radially displaced'from the center of curvature of the outer surface of the well pipe and aplurality of outwardly. bowed: staves extending between and mounted onsaid collar means. 3

2. Thc combination "of claim 1 wherein each said stave hasone end mounted on one said segment of one collar means and. the other end mounted on one said segment of theother collar means.

mounted on any said given segment; l

4. A The combination of claim 1 wherein the radius of curvature of each said segment is approximately Zi'inches.

5. The combination of claim 1 wherein at least four of said 6' segments comprise eachcollar means and only three different circumferential widths form-all diameters of collar means;

6. The combination ofv claim 1 in which, said staves are 3. The combination of claim '2 whereinjonly one stave end is The cutout portions and'53 an abutment engaged by a 6 releasably connected to said segments.

7 The-combination of claim 6 in which each said segment towhich a stave is connected has acutout portion through wh ch the stave extends, a bridge element over the stave and portion of the stave for preventing withdrawal of the stave.

8. The combination of claim 1 in which each said segment has a-circumferential extent of substantially less than 90 with respect to the said predetermined radius of curvature of said segment. H

9. A centralizer for multiple sizes of well pipe comprising at least three axially aligned and spaced for producing at least two pairs of collar means with end collar means and common intermediate collar means, each collarmeans comprised of a multiplicity of more than two separate segments releasably connected together to encircle the well pipe, each segment being circumferentially curved to a predetermined radius of curvature for all of the multiple sizes of well pipe with said radius being'within the range of radii of such multiple well pipe size, and a plurality of outwardly bowed staves extending between and mounted on each pair'of collar means and extending in each direction from said intermediate collar means.

10. The centralizer of claim 9 in which only one stave is mounted on any given segment.

11. The combination of a centralizer-device and a well pipe comprising, a multiplicity of more than two arcuate collar segments having longitudinal edges connected together into a collar of a size encircling the well-pipe, each said collar segment being circumferentially curvedto a predetermined radius of curvature and having a center of curvature radially displaced from the center of curvature of the outer surface of .thewell pipe,-two said collars axially spaced and aligned, a plurality of outwardly bowed stavesext'ending between and mounted on said collars, and at least some of said arcuate collar segments circumfercntially wider than said staves and having a stave mounted thereon with only one stave mounted on a segment. 7

l2. The combination of claim 11 wherein connecting ele- 1 ments are provided along each longitudinal edge of each segment with the elements along one edge opposite .relative to the v n elements along the other longitudinal edge for comprising reversible and mating connecting sections.

13. The combination of claim 11 wherein for accomplishing said connection between segments each segment has one-half of a hinge section along each said longitudinal edge comprised of plural spaced and aligned tubular elements, and hinge pins join the adjacent hinge sections of the multiplicity of arcuate collar segments into each said collar.

' 14. The Combination of claim 13 wherein the tubular elements along one longitudinal edge of each segment are offset relative to the tubular elements along the other longitudinal edge for comprising reversible and mating hinge sections.

15. A centralizer for any size well pipe whose external surface has a curvature within apredetcrmined range of curvatures employing a multiplicity of arcuate. segments each having the same predetermined, curvature which curvature is within said predetermined range of curvatures, and each hav- 'ing an arcuate extend of substantiallylcss than 180 and I means for circumferentially connecting the'segments together 60.

and with a plurality of bowed spring staves each having one of such segments attached to each end, constructed bythe method of, selecting at least three staves with attached segu-ments, selecting an appropriate number of individual segments which are not attached to the ends" of said staves to join with such selected stave segments at each end of the staves to form collars at each end of the staves of a size to encircle the particular well pipe on which the centralizer is to be mounted,

and connecting together the sclectednonattached segments and said attached segments to form-spaced and aligned collars with the staves extending therebetween. 

1. The combination of a centralizer and a well pipe comprising a pair of axially spaced and aligned collar means mounted on the well pipe, each collar means comprising of a multiplicity of more than two separate segments releasably connected together and encircling the well pipe, each segment being circumferentially curved to a predetermined radius of curvature and having a center of curvature radially displaced from the center of curvature of the outer surface of the well pipe and a plurality of outwardly bowed staves extending between and mounted on said collar means.
 2. The combination of claim 1 wherein each said stave has one end mounted on one said segment of one collar means and the other end mounted on one said segment of the other collar means.
 3. The combination of claim 2 wherein only one stave end is mounted on any said given segment.
 4. A The combination of claim 1 wherein the radius of curvature of each said segment is approximately 3 1/2 inches.
 5. The combination of claim 1 wherein at least four of said segments comprise each collar means and only three different circumferential widths form all diameters of collar means.
 6. The combination of claim 1 in which said staves are releasably connected to said segments.
 7. The combination of claim 6 in which each said segment to which a stave is connected has a cutout portion through which the stave extends, a bridge element over the stave and an abutment engaged by a portion of the stave for preventing withdrawal of the stave.
 8. The combination of claim 1 in which each said segment has a circumferential extent of substantially less than 90* with respect to the said predetermined radius of curvature of said segment.
 9. A centralizer for multiple sizes of well pipe comprising at least three axially aligned and spaced for producing at least two pairs of collar means with end collar means and common intermediate collar means, each collar means comprised of a multiplicity of more than two separate segments releasably connected together to encircle the well pipe, each segment being circumferentially curved to a predetermined radius of curvature for all of the multiple sizes of well pipe with said radius being within the range of radii of such multiple well pipe size, and a plurality of outwardly bowed staves extending between and mounted on each pair of collar means and extending in each direction from said intermediate collar means.
 10. The centralizer of claim 9 in which only one stave is mounted on any given segment.
 11. The combination of a centralizer device and a well pipe comprising, a muLtiplicity of more than two arcuate collar segments having longitudinal edges connected together into a collar of a size encircling the well pipe, each said collar segment being circumferentially curved to a predetermined radius of curvature and having a center of curvature radially displaced from the center of curvature of the outer surface of the well pipe, two said collars axially spaced and aligned, a plurality of outwardly bowed staves extending between and mounted on said collars, and at least some of said arcuate collar segments circumferentially wider than said staves and having a stave mounted thereon with only one stave mounted on a segment.
 12. The combination of claim 11 wherein connecting elements are provided along each longitudinal edge of each segment with the elements along one edge opposite relative to the elements along the other longitudinal edge for comprising reversible and mating connecting sections.
 13. The combination of claim 11 wherein for accomplishing said connection between segments each segment has one-half of a hinge section along each said longitudinal edge comprised of plural spaced and aligned tubular elements, and hinge pins join the adjacent hinge sections of the multiplicity of arcuate collar segments into each said collar.
 14. The combination of claim 13 wherein the tubular elements along one longitudinal edge of each segment are offset relative to the tubular elements along the other longitudinal edge for comprising reversible and mating hinge sections.
 15. A centralizer for any size well pipe whose external surface has a curvature within a predetermined range of curvatures employing a multiplicity of arcuate segments each having the same predetermined curvature which curvature is within said predetermined range of curvatures, and each having an arcuate extend of substantially less than 180* and means for circumferentially connecting the segments together and with a plurality of bowed spring staves each having one of such segments attached to each end, constructed by the method of, selecting at least three staves with attached segments, selecting an appropriate number of individual segments which are not attached to the ends of said staves to join with such selected stave segments at each end of the staves to form collars at each end of the staves of a size to encircle the particular well pipe on which the centralizer is to be mounted, and connecting together the selected nonattached segments and said attached segments to form spaced and aligned collars with the staves extending therebetween. 